JPH1113626A - Relief valve mechanism for cryopump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sealing ability by preventing dislocation of an O-ring to hold sealing ability of a relief valve, to improve an automatic regeneration function by eliminating a need for repair and confirmation of dislocation of the O-ring, and to improve working efficiency. SOLUTION: This valve mechanism is constituted such that an O-ring 4 is located at the end part of the exhaust pipe 8 of a cryopump 1 and sealing ability of the relief valve 3 arranged at the external part side of the exhaust pipe 8 is held by the O-ring 4. In this case, a fixing ring 10 having an inside diameter smaller than the outside diameter of the O-ring 4 and height lower than the ring size of the O-ring 4 is arranged on the outer peripheral side of the O-ring 4. The O-ring 4 is pressed against the exhaust pipe 8 by the fixed ring 10 for mounting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryopump used as an ultra-high vacuum pump in an ultra-high vacuum apparatus such as a semiconductor manufacturing apparatus, and more particularly to a cryopump when an internal pressure of a condensed gas reaches a constant pressure during vaporization. The present invention relates to a relief valve mechanism that leaks gas inside to the outside.

[0002]

2. Description of the Related Art As shown in FIG. 3, a cryopump 1 used for removing gas molecules in an ultra-high vacuum apparatus is used.
Is fixedly provided in the vacuum processing chamber 2, and condenses the gas in the vacuum processing chamber 2 on the extremely low temperature solid surface of the cryopump 1, and the condensed gas increases and is vaporized from the solid surface and discharged to the outside. This is performed by opening and closing the relief valve 3 of the cryopump 1.

[0003] The relief valve 3 is an important element for sealing the inside of the cryopump 1 from the outside.
Thereby, the sealing property is maintained. In the figure, 5 is a high vacuum valve, 5a is a high vacuum valve opening / closing joint, 5b is an O-ring for high vacuum valve, 6 is a shield plate, and 7 is a wafer holder.

[0004] To evacuate the vacuum processing chamber 2, first, the inside of the vacuum processing chamber 2 is evacuated to a pressure lower than the atmospheric pressure by a mechanical pump (not shown) for rough evacuation directly attached to the vacuum processing chamber 2. . At this time, the high vacuum valve 5 is closed. When the inside of the vacuum processing chamber 2 reaches a pressure at which the operation of the cryopump 1 can be started, the high vacuum valve 5 is opened,
The remaining gas in the vacuum processing chamber 2 is transferred to the cryopump 1
The inside of the vacuum processing chamber 2 is made ultra-high vacuum by condensing on the solid surface cooled to an extremely low temperature.

[0005] The cryopump 1 uses a cryogen such as liquid helium or a Gifford McMahon type cryogenic refrigerator to form a cryogenic solid surface of about 10K and condense gas on the solid surface. Is a type of vacuum pump that excludes gas molecules from the space. When the amount of gas condensed on the surface of the solid increases during vacuum evacuation and the condensate cannot be further increased, the high vacuum valve 5 is closed once and the cryopump 1 is closed. Is stopped, the temperature of the solid surface is raised to vaporize the gas condensed on the solid surface, and the cryopump 1 is regenerated.

The relief valve 3 of the cryopump 1
Is biased by a spring (not shown) to compress the O-ring 4 and seal the end of the exhaust pipe 8. During the regeneration of the cryopump 1, when the internal pressure of the cryopump 1 rises to a certain pressure due to the vaporization of the condensed gas, the relief valve 3 is pushed up by this internal pressure to open the relief valve 3 to leak the internal gas to the outside. I have to. Then, after the regeneration, the high vacuum valve 5 is opened again, and the ultra-high vacuum is created by repeating the method of condensing gas on the solid surface by making the solid surface extremely low temperature.

However, the O-ring 4 for maintaining the sealing property of the relief valve 3 is provided with a flange 9 at the end of the exhaust pipe 8 of the cryopump 1 as shown in FIG. The relief valve 3 during regeneration of the cryopump 1
Is released, the O-ring 4 may come off at the same time.

When the O-ring 4 comes off in this way,
Even if an attempt is made to evacuate the cryopump after the regeneration of the cryopump, the outside air enters the cryopump 1 from the relief valve 3 and condenses even if the solid surface is lowered to an extremely low temperature, so that the gas in the vacuum processing chamber 2 is condensed. And the inside of the vacuum processing chamber 2 cannot be maintained at a predetermined degree of vacuum, and the O-ring 4 needs to be modified. Normally, the equipment itself has an automatic regeneration function, but it is necessary to check whether or not the O-ring 4 has come off when the cryopump 1 is regenerated, and therefore, the automatic regeneration function is temporarily interrupted. In addition to this, there is a problem that not only the vacuum sealing property is lowered but also the operation efficiency is lowered.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a relief valve mechanism for a cryopump capable of improving the vacuum sealing performance by preventing the O-ring holding the sealing performance of the relief valve from coming off. Is to do.

Another object of the present invention is to improve the automatic regeneration function of the cryopump by preventing the O-ring from coming off, eliminating the need for reworking and confirming the coming off of the O-ring.
An object of the present invention is to provide a cryopump relief valve mechanism that can improve operation efficiency.

[0011]

In order to solve the above-mentioned problems, a relief valve mechanism for a cryopump according to the present invention has an O-ring interposed at an end of an exhaust pipe of the cryopump, and the O-ring is used for the above-mentioned exhaust. In a relief valve mechanism of a cryopump holding the sealing property of a relief valve provided on the outer side of the pipe, an outer diameter of the O-ring has an inner diameter smaller than an outer diameter of the O-ring,
A fixing ring having a height smaller than the ring thickness of the O-ring is attached, and the O-ring is pressed against the exhaust pipe by the fixing ring, and the O-ring is attached to the exhaust pipe by the fixing ring. Even if the relief valve is opened by the internal pressure during regeneration of the cryopump, the O-ring remains pressed against the exhaust pipe by the fixing ring and does not come off from the exhaust pipe. The sealing property of the relief valve can be maintained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
It will be described based on. FIG. 1 is a sectional view showing a configuration of a relief valve mechanism of a cryopump according to an embodiment of the present invention.

As shown, the exhaust pipe 8 of the cryopump 1
A flange 9 is provided at an end of the exhaust pipe 8, and an O-ring 4 is fitted and attached to a pipe end of the exhaust pipe 8 protruding from the flange 9, so that the sealing property of the relief valve 3 is maintained. The relief valve 3 is urged by a spring (not shown) to be attached to the end of the exhaust pipe 8 so as to be pressed against the O-ring 4 from the pipe end, and sealed by compressing the O-ring 4. It has become.

A fixing ring 10 is fitted on the outer peripheral side of the flange 9 of the exhaust pipe 8 from the outside of the O-ring 4. The fixing ring 10 is fitted and attached to the pipe end of the exhaust pipe 8. The O-ring 4 is attached to the exhaust pipe 8 by pressing.

The fixing ring 10 has an O-ring 4
Is slightly smaller than the outer diameter of the O-ring 4 and the dimension of the ring in the height direction is slightly smaller than the ring thickness of the O-ring 4. The relief valve 3 is pressed against and mounted on the relief valve 3 so as to secure a crushing allowance.

The whole structure other than the relief valve mechanism is the same as that shown in FIG. 3, and the description is omitted here.

However, since the O-ring 4 is pressed onto the exhaust pipe 8 by fitting the fixing ring 10 from the outside of the O-ring 4 as described above, the O-ring 4 is not easily detached from the exhaust pipe 8. It is firmly attached and held at the end of the exhaust pipe 8. In this state, the relief valve 3 attached to the outer side in the pipe end direction is urged by a spring (not shown) to compress the O-ring 4 toward the pipe end. The airtightness of the relief valve 3 of the pump 1 is maintained, and the gas can be condensed on the solid surface cooled to an extremely low temperature.

On the other hand, the gas condensed on the solid surface increases,
When it becomes necessary to regenerate the cryopump 1, the high vacuum valve 5 is closed once, the cryopump 1 is stopped, and the temperature of the solid surface is raised. At this time, when the internal pressure of the cryopump 1 rises and reaches a certain pressure, the relief valve 3
Is opened to discharge the vaporized gas to the outside. Also at this time, the O-ring 4 is kept pressed against the exhaust pipe 8 by the fixing ring 10 and does not come off the exhaust pipe 8.

Therefore, even after the regeneration of the cryopump 1, the airtight state of the relief valve 3 can be surely maintained, the occurrence of leakage at the time of evacuation is prevented, and the sealing property of the relief valve 3 is improved. Can be. Further, since the detachment of the O-ring 4 can be prevented, it is not necessary to correct the detached O-ring and confirm the detachment, thereby enhancing the automatic regeneration function of the cryopump and improving the operating efficiency due to a temporary interruption. The drop can be prevented.

[0020]

As described above, according to the relief valve mechanism of the cryopump according to the present invention, the inner diameter is O.
The O-ring is pressed against the exhaust pipe of the cryopump by a fixing ring smaller than the outer diameter of the ring and the dimension in the height direction of the ring is smaller than the ring thickness of the O-ring. The ring can be prevented from coming off.

Therefore, the sealing property of the relief valve can be maintained and the vacuum sealing property can be improved. Also,
Since it is not necessary to rework or check the detached O-ring,
The automatic regeneration function of the cryopump can be enhanced, and the operating efficiency can be improved. You can expect such effects.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a relief valve mechanism of a cryopump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a conventional relief valve mechanism of a cryopump.

FIG. 3 is a cross-sectional view showing the entire configuration of a conventional cryopump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cryopump, 3 ... Relief valve, 4 ... O-ring, 8 ... Exhaust pipe, 10 ... Fixing ring

Claims (1)

[Claims] 1. A relief valve mechanism for a cryopump in which an O-ring is interposed at an end of an exhaust pipe of a cryopump, and the O-ring retains a sealing property of a relief valve provided outside the exhaust pipe. A fixing ring having an inner diameter smaller than the outer diameter of the O-ring and having a height smaller than the ring thickness of the O-ring is attached to an outer peripheral side of the O-ring, and the O-ring is connected to the exhaust pipe by the fixing ring. A relief valve mechanism for a cryopump, which is mounted by being pressed against the cryopump.